The present disclosure relates to a backside-illuminated solid-state imaging device and a manufacturing method thereof, an electronic apparatus using the solid-state imaging device.
In the related art, in a solid-state imaging device, backside-illuminated solid-state imaging devices are suggested for improving photoelectric conversion efficiency or sensitivity to incident light (Japanese Unexamined Patent Application Publication Nos. 2005-347707 and 2005-353631). In backside-illuminated solid-state imaging devices, photodiodes are formed on a semiconductor substrate as a photoelectric converter, pixel transistors and a wiring layer constituting a signal circuit, or the like, are formed on the front surface side of the semiconductor substrate, and light is incident from the rear surface side of the semiconductor substrate.
In the backside-illuminated solid-state imaging device, a portion of a multilayer wiring formed on the front surface side of the semiconductor substrate is provided as a pad electrode, a desired electric potential is supplied to the multilayer wiring due to the fact that an external terminal is connected to the pad electrode. In this case, a wiring bonding is connected from the rear surface side of the semiconductor substrate in the pad electrode which is formed in a portion of the multilayer wiring.
FIG. 6 is a schematic cross-sectional diagram illustrating a main portion of the backside-illuminated solid-state imaging device 100 of the related art. Particularly, the cross-sectional diagram illustrated in FIG. 6 illustrates a region including a pad region 127 formed in the peripheral region of the rear surface side of the backside-illuminated solid-state imaging device.
The backside-illuminated solid-state imaging device 100 includes an imaging region 103 in which photodiodes PD used as the photoelectric converter and a plurality of pixels including a plurality of pixel transistors (MOS transistors) are formed on a silicon substrate 112, and a peripheral circuit portion. In addition, the pad region 127 is formed in the peripheral region. Pixel transistors (not shown) constituting pixels are formed on the front surface side of the silicon substrate 112. Moreover, a wiring layer 113 including wirings 1M to 3M of multilayer structure (three layers in FIG. 6) is formed via an interlayer insulating film 114 in the front surface side of the silicon substrate 112. For example, the wirings 1M to 3M are formed of metal materials such as Cu, Al. In addition, the wiring 3M of the third layer is formed of an Al wiring, and the pad electrode 124 is formed in the pad region 127. A supporting substrate 116 is bonded, for example, by the silicon substrate via an adhesive layer 115 in the front surface side of the wiring layer 113.
On the other hand, an antireflective film 118, a color filter layer 119, and an on-chip lens 120 are formed on the rear surface side of the silicon substrate 112 corresponding to the imaging region 103.
In the pad region 127, an opening 123 for exposing the pad electrode 124 connected to the wiring 3M of the wiring layer 113 is formed. The opening 123 is formed at the same time as the shape forming process of the on-chip lens 120 is performed after forming an organic material constituting the on-chip lens 120, and the opening 123 is formed so that the pad electrode 124 is exposed from the rear surface of the substrate 122. In addition, when the pad electrode 124 is connected to the external terminal, a wire bonding 126, for example, a thin wire of Au (a so-called bonding wire) is connected to the pad electrode 124 which is exposed into the opening 123 in the pad region 127. Thereby, a desired electric potential is supplied from the external terminal.